An MCP client is the part of an AI host, such as Claude, ChatGPT, or a coding agent, that holds one connection open to one MCP server. The host creates a client for every server it talks to, so three connected services means three clients running side by side.
You never configure a client directly. When you connect your agent to Birta, the host creates the client and the connection for you; what you see is a new tool the agent can call.
For where the client sits between the host and the server, see what MCP is and why it matters for publishing.